The present invention relates to an improvement in a recording medium adapted for use in facsimile or measurement.
Among the conventional recording media for use in facsimile or the like, there are known electrolytic recording medium, electrostatic recording medium and electric discharge recording medium consisting of a colored insulator layer formed on a paper base and a metallic conductive layer provided thereon by evaporation and further an uppermost white surface layer. In the electric discharge recording medium obtained by coating a dark-colored carbon or other conductive material on a base such as paper with a binder and further forming a white surface layer thereon, there exists a demerit that the user is discomforted because of odor, smoke or cinder produced during the use. In the electrolytic recording medium having an evaporation conductive layer of aluminum or other metal on a paper base and an electrolytic coloring layer formed thereon, though the above demerit of the electric discharge recording medium is eliminated, there is also a disadvantage that, due to the use of a low-resistance conductive layer of extremely thin aluminum ranging from 500 to 1,000 angstroms, breakdown of the conductive layer may be caused by heat resulting from discharge or similar phenomenon in case a great recording current flow occurs. That is, when such electrolytic recording medium is employed in a device shown in FIG. 1, since the contact between a return electrode (a) and a recording medium (b) is effected by point contact, there arises no problem if the total point-contact area is sufficiently larger than the contact area of a recording stylus (c). Practically, however, the area is not so large. For this reason, in a recording mode, the current density at the point-contact portion immediately below the return electrode (a) becomes high to bring about breakdown of both the conductive layer (d) and the surface recording layer (e) and, in the worst case, burning damage of the paper base (f), thereby causing locally uneven shade or incomplete recording.